Mercury boiler level indicator



NW1 6, 1934- H. STELLING 1,980,012

MERCURY BOILER LEVEL INDICATOR Filed June 30. 1928 VENTOR ATTORNEY Patented Nov. 6, 1934 UNITED STATES.

. v 1,980;012 MERCURY BOILER LEVEL mmcn'roit Henry Stelling, Bayonne, N. J., assignmto The Babcock & Wilcox Company, Bayonne, N. 3., a corporation of New Jersey I Application June 30, 1928, Serial No. 289,543

9 Claims. (Cl. 13-54) ticularly suitable for indicating the mercury level in a mercury boiler, but it is not restricted to this particular use. The device can indicate at a point remote from a boiler, the liquid level in the boiler. The invention will be understood from the description in connection with the accompanying drawing illustrating a portion of a mercury boiler in section with an illustrative embodiment of the invention attached thereto.

In the drawing, reference character 1 indicates a portion of a mercury boiler in which the normal mercury level is indicated by the line 2. The lower side or mercury space of the boiler 1 has one limb of a U-tube 3 connected thereto and the other limb of the U-tube extends above the boiler 1 and terminates in a cock 4. A tube 5 connects the upper portion of the long limb of the U-tube 3 to an indicator 6.

A tube '7 connects the upper or vapor space of the mercury boiler .l to the side of a cistern or container 8 that is provided with a removable plug 9 in its upper side for introducing mercury when desired. The cistern 8 islocated above the boiler 1 and the tube 7 is so arranged that as soon as the mercury in the cistern 8 reaches a predetel-mined level, it will begin to drain back into the boiler. The lower portion of the cistern 8 is connected by the tube 10 to a similar cistern 11 lo-' cated at the same level as the cistern 8. An upwardly extending tube 12 'is connected to the upper portion of the cistern 11 and terminates in a cock 13. A tube 14 extends from the cock 13 to the indicator 6.

The indicator 6 is provided with a glass portion 15 and the tubes 5 and 1e are connected in such a manner that the liquids filling these tubes are visible through the glass. Devices of this character are well known, and it is not thought necessary to describe the same in detail.

The mercury in the boiler 1 filling the same to the level 2 will also fill the U-tube 3 to the level 5,6 in the section 1'7 of the tube 3. The plug 9 'isremoved and a sufiicient amountof mercury is introduced to fill the cisterns 8 and 11 and the tube 10 to the level shown by the solid lines 18 and 19 at which level the mercury will begin to drain into the bo ler through the tube '7 that enters the cistern 8 at the desired point about half way between its bottom and top. A sumcient amount of water is introduced through the cock 4 to fill the tube 3 from the cock 4 to the mercury level 16 and to fill the tube 5 to the line 20 near the middle of the indicator '6. A sumcient amount of oil is introduced through the cock 13 to fill the portion of the cistern 11 above the mercury level 19, the tube 12, and enough of the tube l to cause the contact line between the oil and water to reach the point 20'. The tube 5 is then full of water. The cock 4 is then closed. More oil is added through the cock 13 to fill the tube 14 to this cock; The cook 13 is then closed. The cross section area of the opening in the section I! and that in the indicator 6 are preferably made the same size so that a change in the level 15 will cause an equal change in the level 26.

The operation is as follows: When the mercury level falls in the boiler, 1, ior example. to the line 2, there will be a corresponding fall of the mercury level 16 to a line 16'. water in the upper portion of the long limb of the tube 3 to descend and the water to rise in. the tube 5, thus causing the contact line 2d between the water and oil in the indicator 6 to fall to the line 20'. The oil descends in the tube it and 7 rises in the tube 12. At the same time, the mercury level in the cistern 8is lowered to the line 18' and that in the cistern i1 rises correspondingly to the line 19' in accordance with the amount of oil that has been displaced. The static head due 89 to the differences in the mercury levels in the cisterns 8 and 11 is so slight that the lowering of the mercury level from the line 16 to the line 16' in the tube 3 is almost exactly the same as the amount of lowering of the level from the line 2 5 to the line 2' in the boiler l, and consequently the lowering of the contact line between the water and oil in the indicator 6 from the line 25 to the line 20' is almost exactly the same as the amount by whichthe mercury level has been. 90 lowered in the boiler. The reason for is that the cross section areas of the cisterns 8 and 11 are so large in'comparison to the cross section' area of the section 17 of the tube 3 that a displacement of mercury from the line 16 to the line 16 in the section 17 moves such a mall volume of mercury that a corresponding change in the volume or mercury in the comparatively large cisterns 8 -and 11 will not materially change the mercury levels-in them. The tube '2' connecting the mercury space of the boiler l. to the cistern 8 keeps the two at the same pressure and any vapors passing upwardly through the tube 7 are 5 condensed in the cistern 8, the mercury will drain back into the boiler.

When the mercury level in the boiler l. rises, for example, to the line 2", the same will rise to the line 16" in tube 3, thus causing the contact line 20 between the-water and oil in the indicator 6 to rise to the line 20", causing oil to flow This causes the m -tacting with liquid mercury.

level to the line 19" which will not change the mercury level in the cistern 8 because the mercury will drain through the tube 7 into the boiler 1 after the level 18 is reached.

The vertical distance between the normal mercury level 2 in the boiler and the contact line 20 in the indicator 6 should preferably be to the distance between the levels 18 and, 19 in the cisterns 8 and 11 and the line 20 in the indicator 6 inversely proportional to the specific gravity of water to oil that is in the tubes 5 and 14, so that all the liquids in the whole mercury level indicator system will be in complete balance at normal mercury level in the boiler 1. i

The change oi. contact between the oil and water in the indicator 6 that is visible through the lass 15 rises and falls in accordance with the rise and fall of the mercury level in the boiler 1 so that anobservation of the indicator will show= the amount of mereury'in the boiler.

Withthis device the liquid level in a mercury boiler operating at a high pressure and tempera ture can be safely and accurately indicated. Ordinary level indicators would not be suitable because of the danger of the same breaking. This is especiallytrue of glass indicators. The escape of the liquid or vapor mercury caused by a broken indicator would be very dangerous.

I claim:

1. A mercury level indicator for a mercury boiler comprising two conduits forming a U-tube and containing contacting columns of non-miscible liquids other than mercury, a mercury containing cistern located above the mercury level' insaid boiler, and means to establish communication between said cistern and said boiler above the normal mercury level in said boiler, one of said conduits being connected to said cistern and the other of said conduits being connected to the mercury space of said boiler.

2. A mercury level indicator for a mercury boiler comprising two conduits forming a U-tube and containing contacting columns of non-miscible liquids in which the contacting surfaces of said liquids are movable to indicate the mercury level, means for establishing communication between the mercury space of the boiler and one of said conduits, a mercury containing cistern located above the mercury level in said boiler, means to establish communication between said cistern and said boiler' above the normal mercury level in said boiler, the other one of said conduits being connected to said cistern, and a second cistern interposed in the communication between said first-named cistern and the boiler.

3. In a mercury level indicator for a mercury boiler, two mercury containing cisterns, a connection between the lower portions of said cisterns, aeonnection trom'one of said cisterns to the mercury vapor space of the boiler, two conduits forming a U-tube and containing contacting columns of non-miscible liquids, one of said conduits being connected to the other one of said cisterns, the liquids in each 01' said columns con 4. In a mercury level indicator for a mercury boiler, two mercury containing cisterns located above said boiler, a connection between the lower portions of said cisterns, a connection from one of said cisterns to the mercury vapor space of the boiler, two conduits forming a U-tube and containing columns of non-miscible liquids, one of said conduits being connected to the other one of said cisterns and the liquid in the other conduit contacting directly with liquid mercury.

5. In a mercury level indicator for a mercury boiler, twomercury containing cisterns, a connection between the lower portions of said cisterns, a connection from the normal mercury level of one of said cisterns to the mercury vapor space of the boiler, two conduits forming a U-tube and containing columns of non-miscible liquids, one of said conduits beingconnected to the other one of said cisterns and the liquid in the other conduit contacting directly with liquid mercury.

6. In a mercury level indicator for a mercury boiler, two mercury containing cisterns, 'a connection between the lower portions of said cisterns, a connection from one of said cisterns to the mercury vapor space of the boiler, two conduits forming a U-tube and containing columns of non-miscible liquids, one of said conduits being connected to the other one of said cisterns and the liquid in the other conduit contacting directly with liquid mercury, and means through which the contact point between said'liquids may be observed.

7. In a mercury level indicator for a mercury boiler, two mercury containing cisterns, a connection between the lower portions of said cisterns, a connectionfrom one of said cisterns to the mercury vapor space oi! the boiler, two conduits forming -a U-tube and containing columns of non-miscible liquids, one of said conduits being connected to the other one of said cisterns and the liquid in'the other conduit extending above the normal mercury level in the boiler and contacting with liquid mercury.

8. In a mercury level indicator for a mercury boiler, two mercury containing cisterns, a connection between the lower portions of said cisterns, a connection from one of said cisterns to the mercury vapor space or the boiler, two conduits forming a U-tube and containing columns of non-miscible liquids, one of said conduits being connected to the other one of said cisterns and the-liquid in the other conduit contacting directly with liquid mercury, a chamber of enlarged section in one of said conduits and the other including means through which the contact point between said liquids may be observed.

9. A mercury level indicator for a mercury boiler comprising two conduits forming a U-tube and containing contacting columns of non-miscible liquids other than mercury, a mercury containing cistern located above the mercury level in said boiler, and means to establish communication between said cistern and said boiler above the normal mercury level in said boiler, one of said conduits being connected to said cistern and the other'of said conduits being connected by means of a U-tube to the mercury,-space 01' said 

